One of the forms of radiotherapy treatment, brachytherapy is the modality in which the radiation source is located close to or even inside the patient’s body. In brachytherapy, sources are used that emit low-energy radioactivity capable of traveling short distances and penetrating only a few millimeters or centimeters into the body’s tissues. In other words, the radioactivity is focused on the tissues of interest (e.g. the tumor). To learn more about brachytherapy, see the section “Brachytherapy”.